The present invention involves 8-hydroxy-2H-dibenz[b,f]azepin-2-one dyes which are useful as acid/base indicators and which serve as chromogenic substrates for hydrolytic enzymes. The substrates have superior optical properties and can be used to measure low levels of enzyme concentration.
2,8-disubstituted dibenz[b,f]azepines are known, but only 8 members of this class of compound are reported in the literature. There are also 8 known 2H-dibenz[b,f]azepin-2-ones:
2H-dibenz[b,f]azepin-2-one PA0 1-chloro-2H-dibenz[b,f]azepin-2-one PA0 1-bromo-2H-dibenz[b,f]azepin-2-one PA0 1-nitro-2H-dibenz[b,f]azepin-2-one PA0 3,6,10-trihydroxy-2H-dibenz[b,f]azepin-2-one PA0 1-acetyl-3,6,10-trihydroxy-2H-dibenz[b,f]azepin-2-one PA0 10,11-dihydro-2H-dibenz[b,f]azepin-2-one PA0 4,6,8-tribromo-10,11-dihydro-2H-dibenz[b,f]azepin-2-one
The last is the only reported 8-substituted 2H-dibenz[b,f]azepin-2-one. Its synthesis was described by Teuber and Schmidtke [Chem. Ber. 93, 1257 (1960)]. None of the 2H-dibenz[b,f]azepin-2-ones listed above are pH indicators, although some may be colored.
It is an object of the present invention to provide novel 8-substituted 2H-dibenz[b,f]azepin-2-ones which are suitable for use as acid/base indicators. Incorporation of an ionizable hydroxyl group into the 8-position affords such indicator compounds. It is also an object of the present invention to derivatize said acid/base indicator compounds with suitable enzymatically cleavable groups so as to provide chromogenic substrates for hydrolase enzymes.